Existence of panmictic Hilsa shad (Tenualosa ilisha) populations from two large river ecosystems in Bangladesh revealed by mitochondrial control region

Abstract

The present study was undertaken to estimate genetic diversity and reveal population structure of Hilsa shad (Tenualosa ilisha) from two large river ecosystems, the Padma and Meghna of Bangladesh using mitochondrial control region (D-loop region). Fin tissue samples of 60 individuals were collected from the Padma (ChapaiNawabgonj) and Meghna River (Chandpur). DNA was extracted and D-loopof mtDNA was amplified, purified and sequenced. A total of 35 Sequences (15 Sequences from the Padma and 20 Sequences from the Meghna population) were analyzed and 14 haplotypes were detected. Total16 polymorphic sites were identified that included11 singleton sites and 5 parsimony informative sites. These populations showed high haplotype diversity (h) (0.863 in the Meghna and 0.901in the Padma population). We found low nucleotide diversity (P_i) within each population, 0.0058±0.0039 in the Padma to 0.0063±0.004 in the Meghna population. The shared haplotypes among the two populations were identified as 28.57%, and the rest 71.43% were private haplotypes. Estimate of genetic differentiations (F_st) suggest that the Meghna population of Hilsa was closely related to the Padma population (F_st= 0.058, P=0.07). The TCS genealogy showed three main haplotypes separated by three mutational steps and hap_10 might be the most ancestral haplotype by its internal position in the network. All results suggest panmixia in T. ilisha populations between the Meghna and Padma river populations and thus similar management plan could be useful for these two river Hilsa fishery in Bangladesh.